M 



I N PI 1, \ T-il; V : 



[PUBLIC lirlLI>l\i:s. 





in ench long nixie, from which tV- voice of tlio 



. 

 iblo angle*, have exactlv the 



.lass of the windows 

 ha* 10 groat a ' 



. aimihil.i- 



l:i .1. e tit lixht,* < 



! that force wclc ill 



certain ptuuien, mslaiid'i u-li other ; 



% of light, equally does fO to 



.Hid, as a simple experiment will prove. 



Place 4 gliiis cylinder oil a table, nn>l having struck 



atu:. '.old it iivrr tlm rim of tin; vessel, when 



rate. and produce * sound identical 

 with that of tho f.nk. Then bring another yl. 

 lieM horizontally near the tir.st, in the inaiinur repre- 

 sented in the following figure, when the sound will 

 instantly coane. 



nt.it. 



TliU result of the destruction of sound arises solelv 

 frin the interference of two waves, which neutralise 

 oilier. In a similar manner, the same effect is 

 produced in -a building when two or more waves of 

 sound act on each other after rellection, or by a re- 

 flected wave interfering with one transmitted directly 

 from the speaker. For this reason, there are i 



. in our public buildings in which it is impossible 

 to distinguish the different words .spoken. They aro 

 intermingled with each other, and .so mutually destroy 

 their intemleil eti'ect. 



The r>K)fs of buildings have also a prejudicial 

 and this arises from the unequal reflective powers which 

 they have. In many instances, we may notice deep 

 which, whilst they add to the elegance of the 

 room, materially injure its qualities in an acoustic point 

 of view. Indeed, in every case, th" walls and roof of a 

 building should be as level as possible, provided their 

 cuives an- constructed on proper principles. 

 reflection is thus made equal and regular ; an i 



i of half, or irregular undulations, which are 



.HIM of the interference of sound, is thus avoided. 

 It is a singular fact, that every room, hall, . 



uliar "note" of its own; that is, if a 

 Maker would be well heard therein, he must BO pitch 

 his voice as to suit tho peculiarity of the edifice. To 

 us in the habit of addressing audiences in dif- 

 i places, in rapid succession say, night after ni 

 this in often a source of great anno\an,-e. It thus fre- 

 <|iiently happens, that a really proficient rhetorician 

 utterly fails to impress an audience in some pi 

 whilst he may exceed their most sanguine expect i 

 in others ; and this is sure to occur if the speaker be 

 Midi-exiling an audience in a hall in which he had D 

 l~ fore spoken. It is true, that a singular circumstance 

 iially tends to iem,-,|y this evil; which is, that a 

 shaker can always tell whether his listeners hear him, 

 he l,a-< spoken for a short time. If he have calm- 

 ness and helf-|M>sses.sion, he may r:idiial' lower 

 his tone, to suit the circumstances in which he finds him- 

 self placed. This, however, reipires a skill and dl 

 I'" 11 which- ,is possess. Again, it of ten ha: 

 tluit tho S|-akor hioMeU is incapable, from physical de- 

 fect, i" p-lr. ,1 to Which We ! 



A common fault of jmblic shakers, which no <ppli- 

 -tic principles can ol f too 



rapid an ul 



wand m, quickly, that each interferes wit i. 

 theoflectuf the on-, and a confused jumble | 



to* anlt, f. u. 



of sound results. We caniint 1 



which strict attention must ! paid by those who wish 

 to jiliM.se their hearers; but may cxj>ress an opinion, 

 that however zealous and dc-.in.us of proniotn, 

 l>cne!it of his fellow-creatures a man may be, 

 half his duty if he and opinions in 



an intelligible manner. It is a matter of congratulation 

 to lind, that public authorities, in n-ligi 

 tional circles, are ii v turning their attention 



to this subject, and insisting that a good delivery shall 

 i essential condition to preferment. 



In . the arrangement .,f vocal and instru- 

 mental jK-rformers is of tin. 1 inent. In a 



previous page.t we pointed out tin} fact that cac!. 



w;is j>roduced by a (Infinite amount of vibrations. 



in the Co- i, the bass, tenor, contralto, and 



soprano voices, singing in concert, are throw: 



of sound, each Of which is produced by a different 



nnmlier of vibrations; and the el feet of tin- harmony 



results in all these producing a unison of effect on the 



ear. It is, therefore, the business of a skilful i luetoj 



so to arrange the voices or instruments as that the har- 

 mony shall l)e, as near :is possible, p ;:d his suc- 

 cess will entirely depend on attention to those prin- 

 ciples of which we have just been speaking. Neglect in 

 this respect will destroy the elKciency of :ioir ; 

 whilst attention thereto will frequently improve the 

 - of a choir of otherv. i-ioin. It 

 is a remarkable; fact, that almost the only public edifices 

 in our country which have been properly constructed for 

 speaking and musical purposes, are our i ..nd it 

 i-; more than likely that such results from the fact, that 

 tl.cy rarely present, or need any external embellish- 

 ment, or that their own 1 for their 

 or profit on their an.l .ng able to hear all that 

 is said or sung in the place. M-i'h of the charm of 

 dramatic representation depends on the elocution of the 

 actor; and as this would be wasted if delivered in an 

 unsuitable building, the internal construction is con- 

 sidered as of the utmost importance. We forbear to 



.d comparisons which strike the mind on 

 sidering this fact, with respect to the relative importance 

 of the objects for which our other buildings are elected. 

 On this point we are sure that our readers will a 

 and "a word to the wise" will doubtless be siitt'x 



Having thus spoken of some of the acou?' 

 which prevail in public edifices, we ma\ Ttain 



practical conclusions for the attention of those who have 

 to do with such matters ; and may divide them into two 

 heads namely, that of architectural construction, and of 

 internal arrangement. A perfectly constructed bin. 

 will l>e one in which the audience form a numb 

 circumferences round a common centre, which i- 

 sj>eaker; or when they are so arranged as to assume an 

 elliptic or parabolic form the speaker in this case beiui; 

 the focus, and the walls, in either instance, the 

 phery of the circle, or other curve. The reason of this 

 will 'be belter understood if our readers peruse our 

 remarks on the laws of the reflection of lixlit from 

 spherical and other curved rellectors :* which, as wo 

 have already observed, are equally to be applied in the 

 case of sound. Hut, for the jmrpose of their special 

 application to tho subject we have in hand, we shall 

 offer an illustration showing the directions of the' waves 

 of sound produced by the human voice, or otherwise, in 

 a building constructed after acoustic ju-ineiples, and 

 compare such with the oblong edifices so common in this 

 country. 



In the following figure, wo shall suppose that the solid 

 external curved line represents the KCini-circumfei 

 of a circular hall, and i 



the construction of a church, or other buiidin-,', after tho 

 usual modern plan of building. In the circular build- 

 in.;, the speaker being placed at fl, it follows that every 

 i pla.-i-d on the curved .(, will be c<|iia'ly distant 

 f rom ,S ; and, as sound obeys the law of radial forces, 

 it follows that each individual seated in that curvi, 

 equally well. The same holds good with thu 

 + c OKU, p. a;f>. )A*n,p i;,t<j-v 



